// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)

package org.xbill.DNS.utils;

/**
 * A routine to produce a nice looking hex dump
 * 
 * @author Brian Wellington
 */

public class hexdump {

	private static final char[] hex = "0123456789ABCDEF".toCharArray();

	/**
	 * Dumps a byte array into hex format.
	 * 
	 * @param description
	 *            If not null, a description of the data.
	 * @param b
	 *            The data to be printed.
	 * @param offset
	 *            The start of the data in the array.
	 * @param length
	 *            The length of the data in the array.
	 */
	public static String dump(String description, byte[] b, int offset,
			int length) {
		StringBuffer sb = new StringBuffer();

		sb.append(length + "b");
		if (description != null)
			sb.append(" (" + description + ")");
		sb.append(':');

		int prefixlen = sb.toString().length();
		prefixlen = (prefixlen + 8) & ~7;
		sb.append('\t');

		int perline = (80 - prefixlen) / 3;
		for (int i = 0; i < length; i++) {
			if (i != 0 && i % perline == 0) {
				sb.append('\n');
				for (int j = 0; j < prefixlen / 8; j++)
					sb.append('\t');
			}
			int value = (int) (b[i + offset]) & 0xFF;
			sb.append(hex[(value >> 4)]);
			sb.append(hex[(value & 0xF)]);
			sb.append(' ');
		}
		sb.append('\n');
		return sb.toString();
	}

	public static String dump(String s, byte[] b) {
		return dump(s, b, 0, b.length);
	}

}
